Sealed carton and method of forming



Feb. 7, 1961 c. F. KLEIN ETAL 2,970,525

SEALED CARTON AND METHOD OF FORMING Filed July 18, 1956 2 Sheets-Sheet 1 /nven fors Clarence F K/e/n 6. Sfuan Sex/0n, I.

Feb. 7, 1961 c. F. KLEIN ETAL SEALED CARTON AND METHOD OF FORMING 2 Sheets-Sheet 2 Filed July 18, 1956 .n w, Em m w ME w A .suming inner liners. .been developed which meet the required standards of carton; and

2,970,525 SEALED CARTON AND METHOD OF FORMING Clarence F. Klein, Hartsdale, N.Y., and G Stuart Sexton II, Louisville, Ky., assignors, by mesne assignments, to The Lord Baltimore Press, Incorporated, New York, N.Y., a corporation of Maryland (1959) Filed July 18, 1956, Ser. No. 598,669 2 Claims. (Cl. 93-36) .irnproved types of relatively inexpensive packages which are both highly moisture-resistant and substantially arrtight without requiring relatively expensive and space-con- Various types of paperboard have an improved relatively airtight and sift-proof end seal for a folded box or carton.

Another object of the present invention is to provide an improved method of sealing the end of a folded box or carton.

Another object of the present invention is to provide an improved end flap construction for a folded box or carton.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice. 1

A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings, forming a part of j the specification, wherein:

Fig. 1 is a top plan view of a carton blank according to the present invention;

Fig. 2 is an enlarged fragmentary view of a portion of the carton blank of Fig. 1; Fig. 3 is a perspective view of the upper portion of a partially sealed carton;

Fig. 4 is a perspective view of the upper portion of i the carton of Fig. 3 showing an additional step in the sealing operation;

Fig. 5 is a perspective view. of the upper portion of the i carton of Fig. 3 with the end sealing completed;

vFig. 6 is a diagrammatic view showing the steps of the sealing operation;

'Fig. 7 is an enlarged fragmentary view of the sealed 2,970,525 Patented Feb. .7, 1961 the present invention is shown in Figs. 1 and 2. The blank 1 in its preferred form is made of a suitably moisture-resistant cardboard stock such as a paraflin, resin,

.wax resin or resin emulsion coated stock or extruded lamination or laminated stock. The blank has front panel 2, a rear panel 3, and side panels 4 and 5 joined at scored fold lines 6. A fastening tab 7 is provided at one side of the rear panel 3 to form the body portion of the carton when it is fastened to the outer edge of the side panel 4. Foldable end flap extensions 8 and 9 are provided at the opposite ends of the side panels 4 and 5 and the fastening tab 7, respectively, and they are joined thereto at score lines 10 and 11, respectively. End flaps 12 are provided at opposite ends of rear panel 3 and end panels 13 and 13a are provided at the bottom and top of the front panel 2, respectively. Score lines 14 define the junction of the flaps 12, 13, and 13a with the front and rear panels 2 and 3.

The preferred form of the end flap construction is shown in detail in Fig. 2. The edges of the end flaps are defined by lines 16 out completely through the carton stock but each terminating a short distance from the nearest score line 14 so that a short length 17 of uncut stock is left between the ends of the cut lines 16 and the score fold lines 10 and 14. This uncut portion 17 provides a tighter corner construction in cooperation with the sealing adhesive when the carton is sealed, as will be more fully described below.

In order to provide a tight fit between the folded end flaps when they are folded into overlapping position, the scored fold line for the innermost end flaps may be positioned inwardly of the blank from the fold lines for outer flaps. Thus, in the blank 1 shown in Figs. 1 and 2,

the fold lines 10 and 11 for the end flaps 8 and 9 are formed inwardly of the blank 1 from the fold lines 14 for the end flaps 12, 13, and 13a, as seen in Fig. 2.

An opening tab 19 is formed on the end flap 13a in the preferred embodiment to facilitate the opening of the carton in cooperation with the finger notch 20 in end flap 10 at the same end of the carton. Opening tab 19 preferably is defined by a score line 21 to facilitate folding it upwardly during the opening action and it has suitably rounded corner portions 22 which provide a knife insertion point when it is desired to open the package by slipping a knife blade between the flaps 12 and 13a.

The position of the end flaps in the sealing of the carton is shown in Figs. 3-5.

In Fig. 3 the sealing has been commenced after the formation of the carton body by the attachment of side panel 4 and fastening tab 7 by the folding in of the end flaps 8 and 9 and the folding out of flaps 12 and 13a.

The flaps are now heated by a heater plate 24 and a the adhesive into the fibers of the paperboard. It is obvione that the adhesive may be applied to the opposite flap of the two facing flaps if desired; for example, the adhesive may be applied to the upper face of flap 12 (Fig. 3) in place of its applicationto flap 13a as shown. As the flaps 8 are folded downwardly to the position shown in Fig. 3, the uncut portion 17-between the end flaps tends Fig. 8 is a perspectiveview of the upper portion of the to draw the adjacent cornerportion's of the flaps 8, 12.,

and 13a inwardly toprovide a tight corner A partial tearing of the uncut portion 17 indicated at 22 (Fig.

also occurs as the fiapsutlaie folded'to their final p'osition.-.; Iherweb-like remaining portion of the. uncut po --v tion 17 between the flaps 8, 12, and 13a provides a damming effect for the adhesive 25 and 26 applied to the flaps, resulting in an adequate concentration of the ad- .hesive in the corners of the carton to insure the formation of a relatively tight corner seal.

As seen in Fig. 4, the end flap 12 is now folded downwardly onto the adhesive coating 25 on the surfaces of the end flaps 8 and it is tightly pressed thereagainst by a folder bar 28. As described above, the score line 10' is preferably positioned slightly inwardly of the blank 1 from the score lines 14 connecting the end flaps to their respective panels so that when the end flap 1 2 is foldeddown, its edge will be at the level of the upper surfacesof the end flaps 8. A relatively tight contact, therefore, will be made at this point between the end .fiaps 8 and .12 so that the adhesive 25 on the surfaceofthe flaps S will fill the relatively slight gap therebetween and will therefore provide an airtight seal between the end flaps 8 and 12. The remaining end flap 13a is now folded onto end flap 1%. The uncut portions 17 at the ends of the cut lines 16 defining the edges of end flaps act in the same way as for-the above-described folding of the flaps 8 to dam the adhesive in the corners between flaps 8, 12, and 13a. The fold line 14 at the edge of the flap 13a is preferably formed slightly outwardly of the fold lines 10 of the end flaps S to cause the edge of flap 13a to fold tightly against the previously folded fiaps 8 and 12.

Fig. shows the end portion of the carton 24 in its sealed condition. The end flap 13a is folded and fastened tightly against the end flap 12 with the exception of the unfastened opening tab 19.

In Fig. 6 the steps of the sealing method are show diagrammatically. A suitable conveyor 30 is shown moving the filled packages beneath a series of sealing stations which seal their ends. Although the method is shown sealing only one end of the package, the method obviously can be used to seal both ends successively or simultaneously. v

At the left end of thegconveyor 30 package 31a is passing beneath a heater bar 24 and an adhesive-applying roller 27 with its fiaps folded as shown in Fig. 3 for the initial flap-heating and adhesive-applying steps described above. Thereafter the flap folding bar 28 folds the heated flap 12 against the adhesively coated flaps 8 as is shown with flap 12b of package 31b. Afterthe flap 12b is folded in place, the package is moved past folding bar 29 which folds the remaining end flap 13a against flap 12 as is shown with flap 130 of carton 31c. The carton end flaps have now all been folded and glued into place. Thereafter the carton is moved successively beneath a heater bar 32 and a chilling bar 33 which are resiliently mounted to also apply pressure to the spaced ends of the cartons.

The heater bar 32 heats the end flaps and causes a melting of the thermoplastic adhesive while the flaps are pressed tightly together. This forces the adhesive to flow into all open portions remaining between the flaps to fill them and to provide a tight end flap seal. Immediately thereafter, the carton, such as carton 31d, is carried under chilling bar 33 which continues to hold the end flaps under pressure while causing the adhesive to harden in its sealing position so that a moisture-proof and relatively airtight package end seal results.

Fig. 7 is an enlarged detail View of a corner of the completed sealed package 31d. The originally uncut portion 17 at the end of the cut lines 16 is torn during the folding down of the end flaps Sasis indicated at 22 so that the'corner formed between the end flaps 8, 12, and 13a has no'unnecessary opening and so that the thermoplastic adhesive that is applied easily fills the corner during the initial application of the adhesive and during the subsequent heating and chillingactio'ns the heater bars 32'and the chilling bars 33 The initial heating ofthe end flapspby heater bar 24' causes the initial application of the thermoplastic adhesiveto be a relatively'thin and cvcnly=-'applied' layer. Theadditional heating'and pres sure applied by the heater bars 32 completes the sealing by causing a slight additional spreading of the adhesive into any remaining openings or irregularities between the end flaps. The subsequent chilling action of the chilling bars 33 causes the adhesive to harden in this position to assure the retention of atight carton seal during subsequent handling of the package.

Fig. 8 shows the opening tab 19 being used to open the upperend of the carton. Open tab 19, not being attached to th'e'flap 12,.is'easily grasped by the users fingers indicated at 34 and-bent along score line 21 to an outwardly extending position. Thereafter, the opening tab 19 may be used to tear flap 13a from flap 12 so that finger notch 20 on flap 12 is exposed. The user completes the opening. bygrasping flap 12 at notch 20 and by tearing flaps 12 and 8 open.

Alternately a knife such as is indicated at 35 may be .inserted between flaps 12 and 13a at the rounded corner cutouts 22 and drawn across the package top to separate flaps 12 and 13a.

It will be seen that the present invention provides an improved tightly sealed package and a method of forming it. By using suitably coated or laminated paperboard stock which is relatively airtight and moisture-proof and the sealed ends in accordance with the present invention, a complete package is provided which is relatively airtight and moisture-proof. The combination of the shaping of the carton end flaps with the use of the thermoplastic adhesive and its method of application and distribution provides this relatively airtight seal. The method of forming the airtight seal is relatively simple and is adapted for use on presently used packaging machinery with slight modifications. Thus, the carton blank itself may be formed by the usual cutting and scoring means now used to manufacture folding packages from paperboard, and the application of thethermoplastic adhesive and the related end flap handling are easily accomplished on relatively conventional package folding and gluing machines with the addition of heating and chilling means as described above. When the sealing process is completed, a folded and sealed package results which is moisture-proof, sift-proof, and relatively airtight and which is particularly well adapted for use in packaging foods or other perishable articles. The tightly sealed package is formed using only a single blank of conventional thickness, and all waterproofing or air-excluding inner wrappings may be eliminated, if desired, to simplify the packaging operation. The package is also easily opened by the user even though tightly sealed for storage and shipment.

As various changes may be made in the form, construction and arrangement of the parts herein Without departing from the spirit and scope of the invention and without sacrificing any of the advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, what we claim is:

1. The method of continuously sealing moving. wax impregnated paperboard cartons having a plurality of foldable overlapping end'flaps which have their adjoining edges joined together adjacent to their fold lines which comprises moving said cartons successively pasta heating means and heating the end flaps of each moving carton freeingjthe paperboard fibers from the impregnating wax, thereafter applying a thermoplastic adhesive to at least one surface of the heated end .fiaps of each carton, successiv'ely folding the end flaps along their fold lines into iv an overlapping position thereby severing, at least a portion of the connected portion between-adjacent end flaps and. drawing inwardly the corner. portions of the "cartons adjacent the severed portions to form a tight cornerand a darn for the thermoplastic adhesive atthe corner, heatling and pressingthe end flaps of each moving carton. tov getherand forcing the moltenthermoplastic adhesive to P flow into said; inwardly drawn corners and; the dams formed thereat, and thereafter cooling the end flaps of the moving cartons while holding them under pressure to solidify the thermoplastic adhesive whereby an airtight seal is provided for the carton.

2. The method of continuously sealing wax impregnated paperboard cartons having a plurality of foldable overlapping end flaps which have their adjoining edges joined together adjacent to their fold lines which comprises forming carton blank end flaps by cutting the contiguous edges of the flaps to a point spaced from the flap fold lines, moving said cartons successively past a heating means and heating the end flaps of each moving carton freeing the fibers from the impregnating wax, thereafter applying a thermoplastic adhesive to at least one surface of the heated end flaps of each carton, sue cessively folding the end flaps along their fold lines into an overlapping position between adjacent end flaps and drawing inwardly the corner portions of the cartons adjacent the severed portions to form a tight corner and a dam for the thermoplastic adhesive at the corner, heating and pressing the end flaps of each moving carton together and forcing the molten thermoplastic adhesive to flow into said inwardly drawn corner and the dams formed thereat, and thereafter cooling the end flaps of the moving cartons while holding them under pressure to solidfy the thermoplastic adhesive whereby an airtight seal is provided for the carton.

References Cited in the file of this patent UNITED STATES PATENTS 2,043,897 Levy June 9, 1936 2,107,096 Wesselman Feb. 1, 1938 2,382,573 Moore Aug. 14, 1945 2,437,114 Moore Mar. 2, 1948 2,526,945 Gray Oct. 24, 1950 2,555,315 Carroll June 5, 1951 2,596,224 Eaton May 13, 1952 2,719,093 Voris Sept. 27, 1955 2,727,676 Tilly Dec. 20, 1955 2,760,713 Andrews Aug. 28, 1956 2,761,611 Benschoter Sept. 4, 1956 2,795,364 Benzon-Petersen June 11, 1957 FOREIGN PATENTS 329,706 Great Britain May 26, 1930 

